The solubility of Na3(PO4) is 0.025 M. What is the Ksp of sodium phosphate?

Answer 1

Frankly, I think this is crazy but this must be what you're expected to do. Na3PO4 has no Ksp in my opinion.
........Na3PO4 ==> 3Na^+ + PO4^3-
I........0.025....3*0.025..0.025
C.......-0.025
E.........0........0.075...0.025

Plug that E line into Ksp expression and solve.